Ah-Shi-Sle-Pah Wilderness is located in San Juan County, New Mexico, between Chaco Canyon and the De-Na-Zin Wilderness. The wilderness has multicolored badlands, sandstone hoodoos, petrified wood and dinosaur bones. The BLM Wilderness Study Area (WSA) was declared in May 1992 and would protect an area of about 26.5 km2. The area was prospected by the dinosaur hunter Charles Hazelius Sternberg in the summer of 1921.
Sternberg collected the type specimen of Pentaceratops fenestratus, a ceratopsid dinosaur from the late Cretaceous Period, within the WSA. Fossil collecting here without a permit is prohibited by law. John D. Dingell, Jr. Conservation, Management, and Recreation Act, signed March 12, 2019. It authorizes the establishment of the Ah-Shi-Sle-Pah Wilderness as a component of the National Wilderness Preservation System,. This protects approximately 7,242 acres. (via Bureau of Land Management)